1. Field of the Invention
The present invention generally relates to an electromagnetic switch of a starter, for example, used for a vehicle, and more particularly to an electromagnetic switch wherein a movable contact member is connected with fixed contact members to turn on the switch.
2. Description of Related Art
An electromagnetic switch of a starter is used to start driving an engine of a vehicle by supplying an electric current from a battery to a motor through the turned-on switch. An electromagnetic switch has been, for example, disclosed in Published Japanese Patent First Publication No. H05-126018.
This switch has two fixed contact members and a movable contact member. The fixed contact members are connected with a motor circuit of a starter and a battery, respectively. The movable contact member is fitted to a shaft connected with a plunger so as to be movable with the plunger. When the movable contact member comes in contact with the fixed contact members, the fixed contact members are electrically connected with each other through the movable contact member, the motor circuit receives an electric current from a battery through the contact members of the switch, and a motor is driven. In response to a rotational force of the motor, the driving of an engine is started. After the driving of the engine is continued due to the combustion of fuel, the movable contact member is detached from the fixed contact members, and the driving of the motor is stopped.
The movable contact member is slidably fitted to an end portion of the shaft fixed to the plunger through a set of insulating members. Further, a heated washer is fitted to an end of the shaft and is cooled. Therefore, the washer is tightly fixed to the shaft to prevent the movable contact member from coming out.
However, in the switch disclosed in the Patent Publication, to fix the movable contact member to the shaft, in addition to many parts such as a set of insulating members and a washer, it is required to heat and cool the washer. Therefore, a cost for manufacturing the switch is heightened, and it is difficult to downsize the switch.
In another electromagnetic switch, a movable contact member is directly attached to a shaft without using an insulator. FIG. 1A shows a movable contact member not yet attached to a shaft, and FIG. 1B shows the movable contact member attached to the shaft. As shown in FIG. 1A, a circular flange 110 disposed at an end of a shaft 100 is inserted into a circular hole 210 opened in a movable contact member 200 so as to place a body of the shaft 100 in the hole 210. Then, as shown in FIG. 1B, portions of the contact member 200 surrounding the shaft 100 are pressed towards the shaft 100 to caulk the contact member 200 and to tightly fix the shaft 100 to the contact member 200. The flange 110 and the caulking prevent the contact member 200 from coming out of the shaft 100.
However, in this fixing of the movable contact member shown in FIGS. 1A and 1B to the shaft 100, although the number of parts can be reduced, the caulking operation for the contact member 200 is required after insertion of the shaft 100 into the contact member 200. Therefore, a cost for manufacturing the switch is also heightened.